Circulatory, hypoxemic or traumatic arrest is a significant public health problem cutting across age, race, and gender. A key obstacle for contemporary treatment strategies is the acutely limited time window for effective treatment. Beyond ten minutes after victim collapse, the likelihood of complete physical and neurologic recovery with conventional resuscitation is very low and overall survival for arrest victims is less than ten percent. Stroke presents a similar difficulty, where the effective resuscitation window is very narrow. Likewise, the resuscitation of military and civilian casualties in brain injury and hemorrhagic shock remains one of the most challenging aspects of trauma care. One of the tenets of modern resuscitation is to maintain adequate oxygen delivery to tissues and to maintain cerebral oxygen delivery at a level that meets intracranial neural tissue oxidative needs. The ideal device for monitoring the adequacy of resuscitation in the arrest, stroke and trauma patients should be noninvasive, not only allowing ease of placement but also permitting it to be used in the field and it should provide the clinician with an objective parameter that measures oxygenation at the tissue level in end organs. Near-infrared spectroscopy (NIRS) is a method with these two basic characteristics. The suggested NIRS system with novel sensors designs and sophisticated signal processing will allow a multitude of diagnosis modalities of arrest, stroke and trauma victims: 1. Measurement of local oxygen saturation in extremities to guide resuscitation of victims of arrest and hemorrhagic shock. 2. Measurement of local oxygen saturation in the brain to guide resuscitation of victims of arrest, stroke and brain injury. Furthermore the suggested system is battery operated, small and lightweight and can easily be carried by a paramedic for in-the-field diagnosis and guiding resuscitation efforts. Phase 1 proposes to design and validate signal analysis methods and optimum NIRS sensor configuration that would provide reliable and continuous local tissue saturation measurement for different tissue types. In Phase 2 wireless NIRS system will be developed capable of reliable and continuous measurement of local tissue oxygen saturation in multiple body locations simultaneously for a critical evaluation of local and systemic ischemia during resuscitation. Circulatory, hypoxemic or traumatic arrest is a significant public health problem cutting across age, race, and gender. A key obstacle for contemporary treatment strategies is the acutely limited time window for effective treatment. The project suggests developing a system with novel sensors designs and sophisticated signal processing to allow a multitude of diagnosis modalities of arrest, stroke and trauma victims to support resuscitation in field conditions. [unreadable] [unreadable] [unreadable]